Ferdinand I, Archduke of Austria, with residence in Vienna (after 1521), after 1526 also King of Hungary and King of Bohemia (by inheritance), and after the abdication of his brother, Emperor Charles V in 1556, Holy Roman Emperor 1556-1564. Ferdinand was born 10 March 1503 in Alcala de Henares near Madrid, younger son of King Philip I and Queen Joanna of Castile. Ferdinand died 25 July 1564 in Vienna and was succeeded as emperor and king by his eldest son Maximilian II. His second son became Ferdinand II, Archduke of Austria, ruling Further Austria (Tyrol), and his third son became Charles II, Archduke of Austria ruling Inner Austria (Styria, Carniola and Carinthia).

Ferdinand had been brought up as a staunch Catholic, and vigorously defended his church in the great struggle of his time. And yet he could not stem the rising tide of Lutheranism, either in Germany or in his own domain (Erblande) of the two Austrias, Tyrol, Styria, Carinthia, etc. Eventually he had to tolerate it de facto, particularly in view of the ever-threatening danger of Turkish invasion that made the help of the Protestant estates indispensable. The Peace of Augsburg of 1555 with its formula "whose region his religion" (cuius regio eius religio) would have entitled him to re-Catholicize all his domain, yet political circumstances prevented him all his life from carrying out this plan. Thus Austria remained predominantly Protestant until well toward the end of the century.

With so much the more vigor Ferdinand fought the Anabaptists, who were being denounced as arch-heretics by Catholics and Protestants alike. A great number of mandates were promulgated by Ferdinand against "sectarians and heretics." The first one, dated 20 August 1527, was particularly harsh against the Anabaptists because of "their misuse of the tender corpus Christi" and their custom of "renewed baptism." With this mandate a ruthless persecution set in, in which Ferdinand took a personal lead. One of his first victims was Balthasar Hubmaier; the baron Leonhard von Liechtenstein was asked to deliver this man from his refuge in Nikolsburg. He was condemned, however, officially not because of his Anabaptist faith but rather because of his connections (remote though they were) with the Peasants' War of 1525 in Waldshut. On 10 March 1528, he was burned at the stake in Vienna. In 1527-28 a number of trials against Anabaptists were carried out in Upper Austria (Steyr with six executions, Freistadt, Enns, also Gmunden and Wels); but in view of the tremendous spread of Anabaptism everywhere from Tyrol to Moravia, this method appeared to Ferdinand to be too slow and ineffective. He therefore appointed the nobleman Dietrich von Hartitsch as special "Profos" (commissioner) against all Anabaptists with authority to proceed against them the short way. Von Hartitsch was active particularly in Lower Austria, where within a short time Anabaptism became nearly extinct. Persecutions were ordered in all areas under Ferdinand's jurisdiction, even in the outlying Hapsburg districts (Vorlande) of Alsace, Breisgau, and Württemberg. Everywhere special commissions were set up to make any further spread of Anabaptism practically impossible. The stakes (pyres) burned everywhere; according to one source, in the Inn Valley in Tyrol alone no fewer than 1,000 Anabaptists were burned between 1527 and 1530. In Linz (Upper Austria), for a short period a center of the Brethren under the vigorous leadership of Wolfgang Brandhuber, 70 Brethren were put to death in one procedure, including the afore-mentioned "bishop" Brandhuber (1529). In Brück on the Mur River (Styria) nine brethren were beheaded and three sisters drowned in 1528.

The mandate of the Imperial Diet of Speyer in 1529 against the Anabaptists, ordering death by fire for all heretics throughout the Holy Roman Empire, intensified these persecutions still further and gave them a legal basis. Ferdinand published the corresponding mandate for his domain on 10 May 1529. It is amazing to what minute details Ferdinand himself devoted his attention in this matter. When, for instance, he learned that some noblemen in Lower Austria employed simple "Anabaptists" as farm hands during the season of haymaking, he sent strong reprimands to these lords and ordered them to stop this practice at once. The correspondence with the provincial government of Tyrol in Innsbruck is very detailed as to the proper procedures against the Anabaptists. No mercy of any sort was permitted, and leniency by local judges (many had been quite in sympathy with these earnest Christians) was strongly disapproved, even in cases where members of the lower nobility were involved (see Freyberg, Helene).

The events of Münster 1534-35 prompted even more intensified persecutions. Now Ferdinand had the "argument" that such revolutionary dangers must be prevented by any means; once Anabaptists were in power they would certainly act this (Münsterite) way, all denials of imprisoned Brethren notwithstanding. Tyrol had been the very center of Anabaptist activities at that time, and here persecutions were the most ruthless. Eradication of this "heresy" seemed at first nearly hopeless, all the more so since the Brethren were supported by sympathizers in all the remote mountain valleys. In 1528 the two outstanding leaders, Leonhard Schiemer and Hans Schlaffer, were put to death (see Inn Valley). But soon Jakob Hutter was to fill the gap, tireless in working for his new faith. As life in Tyrol had become so precarious, Hutter began to lead an exodus to Moravia, then the only country in Central Europe where freedom of religion was practiced by the nobles. Here in Moravia (part of the Kingdom of Bohemia) the power of Ferdinand was rather restricted, and Ferdinand's mandates were but very little obeyed. The medieval independence of proud feudal lords still lingered on, giving the Anabaptists the unique chance of a safe refuge. To Ferdinand it was a point of particular grief. In 1535 he gained a temporary success, and for a short time the Brethren were driven out of their places. Some sought refuge in near-by Slovakia; others returned to Germany (see Philippites). But soon the former privileges were restored, in spite of Ferdinand's sharp mandates of 1545, 1548, and 1554, requiring the expulsion of the Brethren. More peaceful development now became possible in Moravia, and for the Brethren began their "Golden Age" (ca. 1550-90).

Elsewhere, however, in the Austrian domain Anabaptism slowly died out by the middle of the 16th century, due mainly to Ferdinand's tireless activities and detailed attention in this direction. Only now and then do we learn of new victims of persecution, such as, e.g., the migrating Brethren from Kaufbeuren, Bavaria, to Moravia in 1545, who were intercepted in Vienna and soon executed there.

In 1551 the Jesuits, champions of the now rising Counter-Reformation, arrived in Vienna; soon thereafter they came also to Prague, Innsbruck, and other places in the Hapsburg realm. However, new conflicts with the papacy (Paul IV) prevented any radical acts by Ferdinand. Thus Lutheranism was still rather strong in Austria at the time of the death of Ferdinand I. Though he had tried hard to create a stronger central government in Vienna, the time was not yet ripe to overcome the particularism of the feudal lords or the relative independence of the thriving cities. (See Rechtsprechung, ML IV.)